I am a graphic designer but a beginner of infographics. I am not sure what is said to be a visual effect and what is not? For example, in network visualization, can I use shadows to make line perception better, or can I use 3D shading or halo effects to highlight some nodes? Is motion a visual effect?
Thanks so much for posting your question on VisGuides. Please, could you elaborate on the reference you used or the source from where this rule come, and in which context do you want to apply it?
This additional information will be helpful to understand the guideline you are interested in.
Sorry. I found this rule in
Stephen Few, “Practical Rules for Using Color in Charts”
Perceptual Edge, February 2008.
I have found that most rules are relatively easy to understand and applicable to many types of charts. In terms of Rule #9, I understand that the 3D effect for the bar chart in the example is not helpful. But when a chart has overlapping objects, I wonder if I can use some mild 3D effects to help see the separations or connections better.
In my original article, the specific visual effects that I referred to were “effects of light and shadow, especially those that are designed to make two-dimensional objects such as bars, lines, and data points, appear three dimensional.” To illustrate this, I provided an example of a bar graph that used effects of light and shadow to make the bars appear three dimensional, which made the bars more difficult to read and compare to one another than standard 2-D bars. As such, the visual effect not only failed to do good; it did harm.
In response to your questions, however, I can expand on this guideline a bit. Everything in a graph – all of its objects and their visual attributes – should support the graph’s purpose and do so in a way that represents the data clearly, accurately, and in a manner that can be perceived with relative ease. Any visual attribute that supports the display in this manner is potentially useful. For example, you mentioned the halo effect as potentially useful. Halo effects can be useful for highlighting objects or for separating objects from their backgrounds in a manner that makes them easier to perceive with accuracy. I often use halo effects to set bubbles on a geographical display apart from their varied backgrounds. Typically, the background of a network diagram is clean and consistent in appearance, however, and therefore halo effects aren’t needed to set nodes apart from their backgrounds, but they certainly could be used to highlight particular objects.
You asked whether it makes sense to use 3-D effects to make it easier for people to discriminate objects that overlap in a visualization. If overlapping objects cannot be avoided and people need to discriminate the objects as well as possible to understand the data, then it might be useful to use some visual effect to support the effort. I find it hard to imagine a case when a 3-D effect would provide the best solution, however, but I’m certainly open to the possibility. Try it and see if it works. Share it with me and others and we’ll let you know if we agree.
The point is that every design choice that you make when creating a data visualization should be considered carefully. Every object and visual attribute should represent the information as effectively as possible. Any time that you include an attribute that carries no meaning, you should only do so because it effectively supports the meaning that is conveyed by something else. If you use a halo effect to highlight an object, then the effect itself carries meaning for it is telling the viewer, “Look at this.” If you use a halo effect to set an object apart from its background to make it easier to perceive it with accuracy, the effect itself carries no meaning, but it makes the meaning that the object carries more perceptible.
To make good design choices, we must understand visual perception: what works for the human brain, what doesn’t, and why. We develop this ability through study and practice. Asking questions, as you have, is an essential part of this process.
I did not expecting to get an advice directly from the most well-known expert and I am almost speechless. Thank you very much for your comprehensive answer, with which I appreciate your rule #9 much more. I can now use *useful" visual effects with some confidence while adhering to the principle of this rule.